Power generation via solar systems that utilize heliostats or similar arrangements provide substantial advantages for very large scale power plants and for applications that require heat rather than electricity. A common form of heliostat utilizes a large number of planar mirrors that direct sunlight onto a common target. The heat can then be used to operate heat engines that generate electricity or the energy can be stored for later use when the sun is not shining.
A substantial fraction of the costs of a heliostat resides in the cost of the mirrors. There is a tradeoff between the size of a mirror and the cost of the mirror. Each mirror must be individually and continuously positioned relative to the target as the sun moves across the sky. The positioning mechanisms contribute substantially to the cost of each mirror; hence, large mirrors are preferred, since fewer positioning mechanisms are required to provide a predetermined amount of heat at the target. However, as the size of a mirror is increased, the mechanical stresses on the mirror and the positioning mechanism resulting from wind loading also increase. These stresses also result in higher structural costs for the mirror frames as well as higher costs for the positioning mechanism, which must now operate against the wind loading. As a result, heliostats are limited to mirrors that are less than 50 ft2.